This application claims the benefit of Korean Application No. 01-74159, filed Nov. 27, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a coupling apparatus used to transmit power.
2. Description of the Related Art
Generally, a photoelectric printer such as a laser printer or a photocopying machine has a development cartridge to form an image. The development cartridge has an integrally formed toner cartridge to supply a toner, a development agent, and a rotatable photosensitive drum. The photosensitive drum forms an electrostatic latent image corresponding to a desired image by a projected light from a laser projection unit. Furthermore, a certain image formed as toner supplied by a toner supply unit, is stuck on the formed electrostatic latent image. In addition, the toner image formed on the photosensitive drum is printed on a paper passing through the photosensitive drum and a settlement roller.
On the other hand, the development cartridge is a disposable one when the toner filled up inside of the cartridge is exhausted. Therefore, the development cartridge is removably connected with a printer body. The development cartridge can have a power transmitted thereto from a predetermined driving unit of the printer body through a coupling apparatus when being placed in the printer body. In other words, a coupling apparatus to drive the photosensitive drum and a roller to supply the toner is installed within the printer. FIG. 1 illustrates one example of the coupling apparatus.
Referring to FIG. 1, a coupling apparatus has a driven coupler 10 connected with one end of the photosensitive drum of the development cartridge, and a driving coupler 20 to transmit power to the driven coupler 10. The driven coupler 10 has a cylindrical body 11, a connection shaft 13 extended from the body 11 and connected with the photosensitive drum, and eight ribs 15 linearly protruding at an outer circumference of the body 11. Each of the ribs 15 is disposed having the same lengths at an interval of 45xc2x0, and integrally formed at the body 11. Moreover, front ends of each of the ribs 15 have sloping sides 15a sloped in a same direction.
The driving coupler 20 is integrally formed at a driving gear 21 having the power from a driving motor (not shown) transmitted thereto. The driving coupler 20 has a cylindrical body 23, and four ribs 25 protruding at an inner circumference of the body 23. The ribs 25 are disposed at a same interval of 90xc2x0. Additionally, front ends of each of the ribs 25 have sloping sides 25a sloped in the same direction with the sloping sides 15a of the ribs 15 when being connected with the driven coupler 10.
For the coupling apparatus having the above structure, the body 11 of the driven coupler 10 is inserted into the body 23 of the driving coupler 20 when being connected with each other. In this case, each of the ribs 25 is inserted between each of the ribs 15 of the driven coupler 10 to be coupled.
However, it is very difficult to form each of the ribs 15 and 25 to have a regular interval due to manufacturing errors. In other words, as illustrated in FIG. 2, the interval T1 of the ribs 15 might be more narrow than the interval T2 of the ribs 25. In this case, like the part A in FIG. 2, the front ends of each of the ribs 15 and 25 are contacted with each other while being sloped, thus connection cannot be easily performed.
Accordingly, it is the object of the present invention to provide a coupling apparatus having an improved structure for easy connection.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other objects of the present invention are achieved by providing a first coupler having a body and a plurality of first ribs protruding at an outer circumference of the first coupler body at a regular interval; and a second coupler having a cylindrical connection portion to embrace and be separated from the body of the first coupler, and a plurality of second ribs protruding at an inner circumference of the connection portion, the plurality of second ribs to be connected between the plurality of first ribs. Each of front ends of the first ribs and the second ribs have sloping sides sloped in a predetermined direction, and one of the first ribs and the second ribs include at least one rib having a relatively longer length than the other ribs.
In an aspect of the present invention, two ribs are relatively longer among the first ribs.
Further, another aspect of the invention provides that two ribs are relatively longer among the second ribs.
In another aspect of the invention, the first ribs are eight in number and disposed at a regular interval and two of them are relatively long with respect to the other ribs, and the second ribs are four in number and disposed at a regular interval.
In an aspect of the present invention, the ones of the ribs close to the at least one relatively longer rib among the first and the second ribs have sides sloping in a different direction from ribs of the corresponding coupler.
Moreover, the at least one relatively long ribs among the first and the second ribs have sides sloping in a same direction with ribs of the corresponding coupler.
Additionally, a driving gear is connected with the connection portion of the second coupler in order to transfer power.
The foregoing and other objects of the present invention may also be achieved by providing a coupling apparatus to transfer power to drive a photosensitive drum disposed at a development cartridge and removably connected with a printer body according to another embodiment of the present invention to accomplish the above object comprises: a first coupler having a body with a plurality of first ribs protruding at an outer circumference of one end of said first coupler body, another end of the first coupler body is connected with the photosensitive drum; and a second coupler having a connection portion embracing and being separated from the first coupler body, and a plurality of second ribs protruding at an inner circumference of the connection portion. One of the first ribs and the second ribs include a rib having a relatively longer length than the other ribs.
In an aspect of this embodiment, the first ribs are eight in number and disposed at a regular interval, and two ribs among them are relatively long with respect to the other ribs.
Further, a driving gear is connected with the second coupler.
Additionally, sides sloping in a same direction with ribs of a corresponding coupler are formed at the front ends of the ribs relatively longer than relatively shorter other ribs among the first and the second ribs, and sides sloping in a different direction are formed at front ends of the relatively shorter ribs.